UPS systems provide reliable, uninterrupted electric power to loads when the main input power supply is disrupted. These systems are typically used to protect computer, storage, processing, telecommunication equipment and/or any other equipment where the interruption of power supply or deviation from regulated power supply specifications can cause disruption, data loss, or injuries.
In a common power architecture of a UPS system, a load is connected through a DC bus to both a main AC-DC power supply and a backup battery. The load is typically powered from the main AC-DC power supply, for example through mains power. If the AC power supply is disrupted, for example, because of a power outage, the load is switched to the backup battery, which ensures continuous power supply. As the backup battery releases its stored energy by discharge, the voltage of the DC bus may significantly drop compared to its value during supply of the AC power. This voltage drop may be amplified when the backup battery has a high discharge rate, such as with lead-acid or lithium-ion batteries. As a result, typical UPS architectures may require a wide operational range of the DC bus voltage, e.g., in the order of tens of Volts. Such a wide operational voltage range may lower the power efficiency and increase cost and complexity of the supply and conversion operations in the UPS system.